But a by-election will not be triggered in the Cyncoed ward as it is less than six months until the next scheduled full council poll, set for May.

Coun Jones, former executive member for the environment and Lord Mayor in 2014-15 , said she is resigning to move to New Zealand to be closer to family.

Margaret Jones has represented Cyncoed since 2004

“I’ve decided to step down to move to New Zealand, in order to be closer to my daughter and grandchildren who live out there,” she explained.

“It has been very hard having them so far away so I can’t wait to be able to see more of them.

“Stepping down as a councillor was not the easiest decision to make, but I would not be doing it were I not confident of a strong Lib Dem team in place to continue our hard work.”

Cardiff Lib Dem leader Judith Woodman said: “I want to thank Margaret for her years of tireless work for our city and our party.

“As a councillor, group whip, executive member and Lord Mayor she has served the people of Cardiff diligently and will be sorely missed.

Cardiff's Liberal Democrat leader Judith Woodman

“It is a testament to her dedication that she’s continued to serve her residents by responding to casework until her very last day as a councillor.

“It’s that very same hard work and dedication that the people of Cyncoed will continue to receive from their Lib Dem team.”

The resignation means that there are now 73 serving councillors in the capital. A vacancy in Llandaff North caused by the resignation of Labour’s Sue White will also not be filled until the next election.

Labour has 39 members, down from 46 after the 2012 election.

There are now 34 opposition councillors, meaning Labour’s majority has increased by one to five following Coun Jones’s decision to quit.